Don't shut off online sales less than one hour before curtain.

You lose connectivity to the internet 20 minutes before curtain, at which point there are 10 seats left.

Our server is still running, and people at home can buy all 10 of those seats, but may buy none.

In that situation, should you sell seats to people who come to the door or not?

If you do sell them, and people bought them online before that, you have oversold.

If you don't sell them, but no one bought online, you could be turning people away at the door and end up with ten vacant seats.

If you cut off online sales two hours before curtain, you can print out the [rsvns] report a minute or two after cutoff. If the server goes down around then, or you lose connectivity, the situation will almost always be remedied within less than half an hour. During that time, no online tickets can have been sold, so you are free to sell whatever seats you know you have left.